Children more than eight years old should be able to enjoy this toy.  They should be careful not to loose the multiple pieces.  There might also be a choking hazard on the smaller pieces.

Creating this toy would be be like making multiple tinker toys with an attachable simple cart/sled.  There would also be weights/baggage.  The costs may be a little higher as a result.  Construction would also be a little complicated due to the many gears and assembly of the multiple dogs.